Clinical Characteristics, Classification and Diagnosis of Depression

Clinical Characteristics, Classification and Diagnosis of Depression

Clinical characteristics, classification and diagnosis of depression

There are two areas covered in this pack:

  • Clinical characteristics of depression
  • Issues surrounding the classification and diagnosis of depression, including reliability and validity

We are looking at major depression which is also known as unipolar depression.

Clinical characteristics of depression

Depression is classified as an affective or mood disorder.

According to a recent survey (ONS, 2010-11) approximately 20% of adults experience symptoms of depression with a higher proportion of women than men. The incidence is higher in divorced or separated individuals.

Major depression is characterised by a cluster of symptoms.

Behavioural (e.g. going out less)

Physical (e.g. poor sleep, agitated)

Cognitive (e.g. negative thoughts about the self and future, suicidal thoughts)

Emotional (feelings such as low mood, guilt)

Diagnosis of depression

In order to be diagnosed with major depression, a doctor or psychiatrist would look for a cluster of symptoms as described in one of the documents that categorise mental health criteria.

There are two well-known ones: the DSM and the ICD.

DSM-V(American Psychiatric Association, APA)- The DSM is used by psychiatrists, particularly in the US but increasingly elsewhere, to diagnose mental illness according to clusters of symptoms.

ICD-10 (World Health Organisation, WHO)- The ICD has become similar to the DSM over time but is intended for use by health practitioners more generally. It is also an international system for assessing how prevalent (how much of) a disorder there is in a country with a view to reducing the amount.

DSM / ICD
At least one of the following, occurring most days, most of the time for at least two weeks:
  • Persistent sadness or low mood
  • Marked loss of interest or pleasure
PLUS at least five of these: / All three of the following must be present:
  • Persistent sadness or low mood present most days, most of the time for at least two weeks
  • Loss of interest or pleasure
  • Fatigue or low energy
PLUS most of the following to give a total of at least 8:
Disturbed sleep / Disturbed sleep
Loss of appetite or weight / Loss of appetite
Fatigue, low energy / Poor concentration and attention
Agitated or slower movements / Low self-esteem and self-confidence
Poor concentration, hard to make decisions / Feeling guilty and unworthy
Feeling worthless or inappropriate guilt / Suicidal thoughts, acts or self-harm
Suicidal thoughts or acts / Bleak, pessimistic views of the future

Issues with classification and diagnosis

Validity

Validity refers to the extent to which a psychological measure can be said to be measuring what was intended.

Concurrent validity refers to the extent of agreement between two measures taken at or about the same time. If measures agree, then there is high concurrent validity or low if they do not agree.

Wittchen et al. (2001)

A study was carried out across Germany on a target day in 1999.

20,421 patients (aged 15-99) who attended their doctor’s surgery on that day filled out a depression screening questionnaire, which included criteria from both the DSM and ICD.

The researchers found that 4.2% of the patients fulfilled the criteria for a major depressive episode according to DSM-IV; considerably higher rates of 11.3% were obtained using the ICD-10 criteria. Therefore, 2–3 times more people had symptoms of depression based on the ICD-10 criteria compared to the DSM-IV, although most of this excess was caused by people with mild depression according to the ICD-10.

There is general recognition in the medical community that there is a higher threshold for diagnosing depression with DSM compared to ICD.

The 633 doctors in the study looked at the depression screening questionnaires completed by their patients only. From looking at the questionnaires, the doctors decided whether depression was definite or probable, or whether the patient was not depressed.

The doctors' decisions about definite or probable depression showed that 75% of all DSM and 59% of all ICD-10 diagnoses were recognised by the treating physician as depression. However, doctors also diagnosed definite depression in an additional 11.7% of patients who did not meet either ICD-10 or DSM-IV criteria.

The findings of this study could be interpreted in a number of ways by reflecting on the validity of the clinical characteristics stated in ICD and DSM or alternatively by considering whether the doctors themselves were at fault with regard to making valid diagnoses.

Comment on the concurrent validity of ICD-10 and DSM-IV.

Comment on what the Wittchen study may tell us about the validity of the clinical characteristics of ICD and DSM. Make separate comments about the DSM and ICD.

Comment on what the Wittchen study may tell us about doctors’ abilities to make valid diagnoses of depression.

Comment on the possible effect on the patients arising from the issues above.

Reliability

A reliable diagnosis would mean that different psychiatrists should agree on what disorder a particular person has because of the presence of pre-determined symptoms.There should be high inter-rater reliability.

Research by Beck (1961) demonstrates this issue, he looked at the inter-rater reliability between two psychiatrists when examining 154 patients and found that it was as low as 54% meaning there were as many as 71 cases that they failed to diagnose in the same way.

To diagnose depression, a clinical interview is used. Here are some of the ways to test reliability.

  • Joint interviews – a patient is interviewed by a clinician while others observe (either in person or by reviewing a tape). They make independent ratings. This is a measure of inter-rater reliability.
  • Another measure of reliability is test-retest. The same patient is interviewed at two different times by different interviewers.

Levels of reliability tend to be lower for test-retest even if the same questions are used. Suggest a reason for this.

The table below shows the results from three studies assessing the reliability of the DSM for diagnosing depression.

Study / Sample size / Type of reliability / Correlation coefficient
Zanarini et al., 2000 / N=52 / External reliability: 7-10 day test-retest / 0.61
Zanarini et al., 2001 / N=45 / Researcher reliability: inter–rater observed live / 0.90
Lobbestael et al., 2010 / N=151 / Researcher reliability: inter-rater using an audio tape / 0.66

Comment on the reliability of diagnosis using the DSM including the effect of the type of reliability test used

Even if diagnoses are reliable, they are not necessarily valid. Briefly explain why this is so.

Cultural relativism

Cultural relativism in relation to mental health refersto the belief that mental disorders need to be understood in the context of the culture of the sufferer.

The newer versions of the ICD and DSM have tried to deal with issues of cultural relativism but despite this the issue is still is one of the biggest controversies surrounding diagnosis and classification.

Davidson and Neal (1994) believe that in Asian cultures, for instance, people are praised for showing no expression of emotional turmoil. People tend to display physical symptoms of depression instead. Kua et al (1993) reported that 72% of people in China who first presented with chest or abdominal pains or headaches were later found to have a mental health problem.

In some countries, there is no word for ‘depression’.

Comment on the validity of classifying and diagnosing depression cross-culturally.

Comorbidity

Another issue is comorbidity, which means that individuals may have more than one disorder at the same time. For instance, according to a survey in the US, approximately half of those diagnosed with depression have other problems as well such as anxiety, substance abuse, ADHD and post-traumatic stress. The difficulty for the classification systems is that these problems are listed under different headings.

Co-morbid disorders / % of people also suffering with depression
General anxiety disorder / 17%
Agoraphobia / 16%
Specific phobia / 24%
Social phobia / 27%
Panic disorder / 10%
Post-traumatic stress disorder / 19.5%

Based on this knowledge, comment on the potential difficulties of reaching a valid diagnosis for major depression.

Comment on the possible effect on reliability of diagnosis.

Comment on the implication for treatment.

Consequences of being diagnosed with depression

Labelling

Being associated with the label ‘depression’ can have both positive and negative consequences for the individual. Mental illness labels can remain even when the problem has gone. If someone breaks a bone, the person is not considered to be ‘in remission’ (still has the problem but it has temporarily gone away). The following issues can arise from labelling. What would each one mean for someone with depression?

  • Self-fulfilling prophecy
  • Sick role
  • Prejudice and discrimination

Perry (2011) points out that those close to a person, such as family or work colleagues, might support them and relieve them of some responsibilities appropriate for the sick role. On the other hand, there could be more rejection by acquaintances and strangersif the label is known.

Labels can have both positive and negative consequences. The label could lead to an appropriate treatment and to being cared for. However, it could also stay with that a person once they have recovered and influence how they perceive themselves and how they are perceived or treated socially.

Other issues with classification and diagnosis

Benefits of diagnosis

Being diagnosed with depression has benefits – what are these benefits and how important are they?

Gender and diagnosis

Women are more likely than men to be diagnosed with depression.

Do you think this difference reflects a genuine difference in incidence of depression?

If not what could be the reasons for more women being diagnosed as men? What does this suggest about the validity of diagnosis?

EXAM PRACTICE AND GUIDANCE

Exam Practice: Outline the Clinical Characteristics of Depression (5 marks)

To be diagnosed with ______depression, a person must display a persistent ______mood for at least two ______, and ______other symptoms including sleep disturbance, weight gain or loss, loss of ______, loss of interest in pleasure activities, difficulty in making decisions, excessive ______for real or imagined deeds, and thoughts of or specific plan or attempt at ______.

It is useful to see how depression affects the whole person, and the symptoms can be separated into four categories . ______(sadness, anxiety etc), ______(pessimism, guilt etc), ______(low energy, crying, neglect of personal appearance) and ______(disturbed appetite, constipation, sleep disturbance etc.)

EXAM Q: Discuss issues related to the classification and/or diagnosis of depression. (8 plus 16 marks)

MARK SCHEME

AO1 = 8 marks

Depression is classified as an affective (mood) disorder. For AO1 credit, students need to identify issues related to the classification and/or diagnosis of depression. The Specification directs them towards reliability and validity of C & D so these are likely to form part of the answer. Likely material includes:

  • The reliability of ICD and DSM classification systems
  • The reliability of diagnosis between different clinicians
  • The benefits of diagnosis in accessing support/treatment
  • The problem associated with diagnosis such as labelling and adopting a sick role
  • The validity of diagnosis, e.g. the problem of co-morbidity with other disorders
  • Culture and gender differences in symptom presentation

Depression is diagnosed by the existence of 5 symptoms which should be present for a two week period on all or most days. Students who merely present lists of signs and symptoms of depression, (e.g. depressed mood most of the day nearly every day, diminished interest or pleasure in activities) or who describe classification systems are not addressing the issues surrounding diagnosis and classification. Such material can gain a mark in the rudimentary band. However students who use symptoms effectively to discuss/illustrate issues can receive marks across the range. Examiners should be mindful of a depth/breadth trade-off – students can describe a few issues in detail or more issues in less detail. There is considerable overlap between the issues of classification and diagnosis.

AO2/3 = 16 marks

Credit is awarded for a discussion of the issues identified. This is likely to focus on the importance of reliable and valid classification & diagnosis and the consequences of unreliability etc. For example:

  • Depression is often co-morbid with other disorders in adults, notably anxiety and alcoholism as well as with illnesses such as cancer (e.g. about 27% of sufferers have social phobias). Co-morbidity occurs in children with conduct disorders and disruptive behaviour. This is important as establishing the primary disorder influences the treatment offered.
  • Diagnosis can produce benefits in access to treatment, but labelling can have negative effects, on employment prospects, motivation etc.
  • Two people can be diagnosed with depression but show different symptoms with little overlap.
  • Gender bias - diagnoses of depression are more common in women which could reflect diagnostic bias or the reluctance of men to present with symptoms.
  • Cultural differences in symptom presentation (e.g. physical/somatic presentation in non-Western cultures).

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